Device for collecting pollution on a water surface

ABSTRACT

The invention relates to a collecting device ( 1 ) for pollution on a water surface ( 9 ), the collecting device ( 1 ) including tight side walls ( 11 ), a tight end wall ( 12 ), a top portion ( 13 ), floating means ( 2 ), an inlet portion ( 15 ) and an aft collecting portion ( 17 ), and the collecting device ( 1 ) further including a channel portion ( 16 ) between the inlet portion ( 15 ) and the collecting portion ( 17 ), and the bottom portion of the collecting device being capable of through-put.

CROSS-REFERENCE TO RELATED APPLICATIONS

This United States application claims priority to Norwegian Patent Application No. 20111705 filed 9 Dec. 2011 and to Norwegian Patent Application No. 20121333 filed 13 Nov. 2012, both of which are incorporated herein by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Non-applicable

THE NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT

Non-applicable

BACKGROUND OF THE INVENTION

The invention relates to a collecting device for pollution on a water surface. More particularly, the invention relates to a collecting device of the kind that is connected to a towable boom, the collecting device being positioned in the collecting portion of the towable boom in order to concentrate the pollution further so that it may be transferred to a suitable container or collecting unit by means of a pump.

It is known within the art to use booms to limit the adverse effect of oil pollution on a water surface and to collect the pollution. A boom is characterized by being provided with a floating body and with a skirt. The floating body forms a barrier above the water, and the skirt, which is weighed down by a suitable weight, forms a barrier under water. To be able to follow the motion of the waves, the floating body and the skirt may be constituted by an elastic material such as a plastic material. The floating body may further be inflatable. This has the advantage of the boom taking up relatively little space during storage, transport and deployment, whereas it gets it full volume when being applied.

A boom may be towed through an oil slick for the oil to be concentrated in a portion of the boom in order thereby to make it easier to collect the oil with, for example, a pump or a so-called skimmer. For such towing, one but preferably two vessels may be used, towing the boom by its free end portion. The patent document WO 02/12636 discloses how a boom can concentrate an oil spill, and indicates a solution to how this may be collected. The patent document NO20110127 discloses another boom which is suitable for towing.

It is known in the art that a boom may be provided with a tight bottom, in particular in its collecting portion. Such a boom is termed an oil trawl. It is further known that a net may be used instead of a tight bottom. Such a boom is termed a V-boom or a net boom.

There are several drawbacks to the known types of booms, and it varies how effective they are in relation to their purpose. There is a limit to how large a wave height they can be used in before the oil will pass or escape the boom. On accumulation of oil and water against the boom, the boom will belch, meaning that the oil is forced down into the water at the boom and then carried under the skirt and past the boom. Towing of the boom takes place at low speed and, generally, there are two vessels that will need to coordinate their movements for the boom to maintain its shape which, viewed from above, takes a horseshoe shape or a U-shape.

When the known booms which form, in the main, a U-shape are being towed, the sides of the boom are referred to as arms and the area between the free end portions of the arms is referred to as the front opening of the boom. The collecting efficiency of the boom and how large an area the boom may collect across are determined by the width of the front opening and the towing speed of the vessel or vessels, among other things.

It is also known that, besides the wave height, the towing speed is limited by the deep-draught of the skirt. In the length portion that constitutes the bottom portion or the collecting portion of a U-shaped, towed boom, there will be a considerable water resistance and the water resistance increases with the deep-draught of the skirt. This water resistance will also build up a bow-wave pressure in front of the front opening of the boom. The bow-wave pressure has an obstructive effect on pollution which should, desirably, go into the boom, as the water with the pollution will be deflected and pass on the outside of the boom. To counteract this, it is known to have an opening in the collecting portion of the boom, where water and pollution may discharge from the boom. It is also known that it is advantageous to place collecting equipment in this opening in the collecting portion, as the pollution will be the most concentrated in this portion.

The patent document NO19770862 discloses a bag for collecting oil pollution on a water surface. The oil pollution is concentrated by a boom being towed across the water surface. The collecting bag is positioned at the bottom of the boom. The bag includes a top portion, a bottom portion, a side portion and an end portion, which are all constituted by a tight material. To prevent the bag from taking a round shape when being towed, meaning that the bottom portion will have an unnecessary deep-draught, the bag is provided with tension-absorbing members at the opening of the bag. The tension-absorbing members may be constituted by chains. The chains are attached, at one end, to the lower portion of the bag and are attached, at the other, upper end, to a floating element spanning the opening of the bag. The bag may further be provided with longitudinal, tension-absorbing members from the opening of the bag and aft in about half the length of the bag. The longitudinal, tension-absorbing members are attached to the top portion and the bottom portion. The longitudinal, tension-absorbing members form bulk heads, and the bulk heads may be constituted by a tight material, a reticulate material or a perforated material. Aft in the top portion, the bag is provided with an opening for a pump. The patent document states that the pump-out capacity may be adjusted to be so large that accumulation and turbulence in front of the opening of the bag are avoided. The pump-out capacity may be increased further so that a certain suction effect is created.

Herein, pollution means, but is not restricted to, an oil floating on a water surface, chemicals, solids in particulate form and loose objects. A solid in particulate form may be dust or it may be an absorbent which in itself contains pollution. Loose objects may be rubbish such as small and large pieces of plastic, objects such as tin cans, cans and ropes, or they may be natural objects such as driftwood. The invention may also be used to concentrate live or dead biological material such as seaweed and kelp, algae and crustaceans such as krill and red feed, when it is naturally present or has been brought to be present on or right below the water surface so that it may be intercepted by a boom.

BRIEF SUMMARY OF THE INVENTION

The invention has for its object to remedy or reduce at least one of the drawbacks of the prior art or at least provide a useful alternative to the prior art.

The object is achieved through features which are specified in the description below and in the claims that follow.

In a first aspect, the invention relates to a collecting device for pollution on a water surface, the collecting device comprising tight side walls, a tight end wall, a top portion, floating means, an inlet portion and an aft collecting portion, and the collecting device further including a channel portion between the inlet portion and the collecting portion, and the bottom portion of the collecting device being capable of through-put in its channel portion and collecting portion.

The collecting device may comprise at least one friction element extending from the inlet portion through the channel portion. The friction element may further extend to the end wall. The friction element may be constituted by a material selected from a group comprising a tight material in cloth form; a net; a netting; and a perforated material in cloth form.

At its upper edge portion, the at least one friction element may be attached to the top portion. In one embodiment, the at least one friction element may be releasably attached at its upper edge portion to the top portion. At its lower edge portion, the at least one friction element may project freely into the water. In one embodiment, at its lower portion, the friction element may, in a portion, be attached to a shape-stabilizing element capable of through-put.

In its inlet portion, the collecting device may be provided with a frame set substantially vertically in its position of application. At its forward, lower portion, the friction element may be attached to the lower portion of the frame.

In one embodiment, the at least one friction element may be attached at its side portions to the side walls of the channel portion of the collecting device. The at least one friction element may be releasably attached at its side portions to the side walls of the channel portion.

The top portion of the collecting device may be constituted by a tight material in cloth form.

The invention also relates to a boom arranged to concentrate pollution on a water surface, the boom being provided with an opening in a collecting portion, wherein the boom may be provided with a collecting device as described above.

BRIEF DESCRIPTION OF VIEWS OF THE DRAWINGS

In what follows, examples of preferred embodiments are described, which are visualized in the accompanying drawings, in which:

FIG. 1 shows a perspective view of a collecting device in accordance with the invention;

FIG. 2 shows, on a different scale, an end view of the collecting device;

FIG. 3 shows, on the same scale as FIG. 2, a front view of the collecting device;

FIG. 4 shows, on the same scale as FIG. 2, a top view of the collecting device;

FIG. 5 shows, on the same scale as FIG. 2, a side view of the collecting device;

FIG. 6 shows, on the same scale as FIG. 2, a bottom view of the collecting device;

FIG. 7 shows the same as FIG. 6, but in another embodiment;

FIGS. 8A-B show schematically and in a simplified manner, on a somewhat smaller scale than FIG. 2, A: a cut-away perspective view of the collecting device in an alternative embodiment, and B: a cut-away side view of the collecting device;

FIGS. 9A-B show the same as FIGS. 8A-B, but in another embodiment;

FIGS. 10A-B show the same as FIGS. 8A-B, but in yet another embodiment;

FIGS. 11A-B show the same as FIGS. 8A-B, but in yet another embodiment; and

FIG. 12 shows the same as FIG. 6, but in another embodiment.

DETAILED DESCRIPTION OF THE INVENTION

In what follows, structural features that are essential for the understanding of the invention will be explained.

In the figures, the reference numeral 1 indicates a collecting device for pollution floating on a water surface 9, the pollution having been concentrated by a boom (not shown). The collecting device 1 includes two side walls 11, 11′, an end wall 12 and a top portion 13. At the front end of the collecting device 1, the side walls 11, 11′ and the top portion 13 form an inlet portion 15. At the aft end of the collecting device 1, the side walls 11, 11′ and the top portion 13 form a collecting portion 17.

The collecting device 1 is kept floating in the water surface 9 by means of floating means 2. To keep the inlet portion 15 stable in shape, the collecting device 1 is provided, in its inlet portion 15, with a frame 4 of substantially vertical orientation in the position of application thereof. On its sides, the frame 4 is attached to forward floating means 20. At a front edge, the top portion 13 is attached to the upper portion 41 of the frame 4, see FIG. 5. The top portion 13 is thereby lifted up from the water surface 9 in the inlet portion 15, so that a pollutant may pass under the upper portion 41 of the frame into the collecting device 1 as this is being pulled forwards in the water.

In its collecting portion 17, the collecting device 1 is provided with a frame 5. On its sides, the frame 5 is attached to aft floating means 22. The frame 5 is arranged to carry a pump (not shown) and other equipment for pumping pollution, such as oil, from the collecting device 1 into a container (not shown) or another suitable collecting unit.

The side walls 11, 11′ and the end wall 12 are constituted by a tight material. The tight material may be a material in cloth form, such as a plastic material or a fibre-reinforced plastic material. In one embodiment, the top portion 13 may be constituted by a tight material of the same kind as that of the side walls 11, 11′ or the end wall 12. In an alternative embodiment, the top portion 13 may be constituted by an open material such as a net or a perforated cloth. The alternative embodiment may be suitable in calm waters or for use in a river and has the advantage of the weight of the collecting device 1 being reduced.

In one embodiment, a substantially vertical friction element 3 projects down from the top portion 13, and the friction element 3 extends from the inlet portion 15, in the direction of and substantially to the collecting portion 17. In what follows, the portion of the collecting device 1 between the inlet portion 15 and the collecting portion 17 will be referred to as a channel portion 16. Several friction elements 3 may be arranged side by side. In the FIGS. 1, 3, 6, 7 and 12, three vertical friction elements 3 are shown. The friction elements 3 are attached, at their upper edge portions 31, to the top portion 13. In an alternative embodiment, the friction element 3 may be releasably attached to the top portion 13. The friction element 3 may be attached to the top portion 13 by means of a zip of a type known per se (not shown). At its upper edge portion 31, the friction element 3 may be provided with a plurality of through holes reinforced with grommets (not shown) to enable attachment of the friction element 3 to the top portion 13 with one or more strings. The person skilled in the art will also know of other ways of releasably attaching the friction element 3 to the top portion 13.

At their front edges, the vertical friction elements 3 are attached to the upper portion 41 and lower portion 43 of the frame 4. The lower edge portions 33 of the friction elements 3 are provided with a longitudinal weight element (not shown). The weight element may be constituted by a lead line of a kind known per se or by a chain. The lower edge portions 33 are attached to a shape-stabilizing element 6 connecting the lower edge portions 33 and maintaining the spacing between the lower edge portions 33. The shape-stabilizing element 6 is shown schematically in the FIGS. 3, 6, 7 and 12 as a net. The net 6 may further be attached to the lower edge portion(s) of one or both of the side wall(s) 11, 11′. In the longitudinal direction of the collecting device 1, the net 6 may span the major part of the edge portions 33 as shown in FIG. 7, or the net 6 may be attached to portions of the edge portions 33 as shown in FIG. 6. In an alternative embodiment, the shape-stabilizing element 6 may be constituted by wires, lines or ropes extending between the edge portions 33 and the lower edge portions of the side walls 11, 11′. It is essential to the invention that the shape-stabilizing element 6 is capable of through-put to water in the channel portion 16. In a further alternative embodiment, the collecting device 1 is not provided with a shape-stabilizing element 6 (not shown). The lower edge portions 33 of the friction elements 3 then project freely down into the water and are held in position by the longitudinal weight element. One vertical friction element 3 creates two internal, longitudinal channels in the inlet portion 15 and channel portion 16 of the collecting device 1. Two friction elements 3 create three channels, three friction elements 3 create four channels, and so on.

The friction elements 3 may be constituted by a tight material in cloth form. In an alternative embodiment, the friction elements 3 may be constituted by a net, such as a seine. In a further alternative embodiment, the friction elements 3 may be constituted by a netting. In a further alternative embodiment, the friction elements 3 may be constituted by a perforated material in cloth form.

The invention is shown in a further alternative embodiment in FIG. 12. In this embodiment, the collecting device 1 is provided with one or more substantially vertical friction elements 3 extending from the inlet portion 15 to the end wall 12, through the channel portion 16 and the collecting portion 17. At its lower portion, the collecting portion 17 may be provided with a shape-stabilizing element 6. The friction element 3 may be releasably attached to the top portion 13.

The invention is shown in further alternative embodiments in FIGS. 8-11. In two of these embodiments, the collecting device 1 is provided with one or more friction elements 3′ extending from one side wall 11 to the other side wall 11′ from the inlet portion 15 to the collecting portion 17 in the channel portion 16, see the FIGS. 9 and 11. In two of these embodiments, the collecting device 1 is provided with one or more friction elements 3′ extending from one side wall 11 to the other side wall 11′ from the inlet portion 15 to the end wall 12, through the channel portion 16 and collecting portion 17, see the FIGS. 8 and 10.

In the embodiments shown in the FIGS. 8-11, the friction element 3′ may be releasably attached, at its side portions 31′, 33′, to the side walls 11, 11′. At its side portions 31′, 33′, the friction element 3′ may be attached to the side walls 11, 11′ by means of a zip of a type known per se (not shown). In its side portions 31′, 33′, the friction element 3′ may be provided with a plurality of through holes reinforced with grommets (not shown) for the friction element 3′ to be attached to the side walls 11, 11′ with one or more strings. The person skilled in the art, will also know of other ways of releasably attaching the friction element 3′ to the side walls 11, 11′.

In the embodiments that are shown in the FIGS. 8-11, the shape-stabilizing element 6 constitutes a friction element 3′. It is essential to the invention that the lowermost friction element 3′/shape-stabilizing element 6 is capable of through-put to water in the channel portion 16.

The collecting device 1 is attached to a boom of a kind known per se (not shown), at a gate or opening in the collecting area of the boom. The boom may be designed to be towed forwards by one or more vessels. Alternatively, the boom may be fixed to the banks of a river, so that fluvial water will flow through the boom. The boom may be attached to the forward floating means 20 of the collecting device 1 or to the frame 4 of the collecting device 1. Pollution on the water surface 9, such as oil pollution for example, is concentrated by the boom and will flow into the inlet portion 15. Inside the collecting device 1, the pollution will be guided aft towards the collecting portion 17. The pollution is kept within the collecting portion 17 by the tight side walls 11, 11′ and the tight end wall 12. In its longitudinal direction, the top portion 13 is provided with at least one floating means of a kind known per se (not shown) and will float, in the channel portion 16 and in the collecting portion 17, on top of the pollution.

As the boom with the collecting device 1 is being towed through a polluted area, an increasingly thicker layer of pollution will build up in the collecting portion 17. The layer of pollution is defined downwards by a transition zone between water and pollution. In the art, this transition zone is termed a shear layer. If the pollution is constituted by oil, experience has shown that oil will be entrained by the water when the difference in velocity between the oil phase and the water phase is larger than about 0.41 m/s (0.8 knots). This is referred to as the collector belching. In the art, the term ‘first loss’ is also used about this.

It has turned out that the friction elements 3, 3′ lead to water with pollution being slowed down within the collecting device 1 as the water and the pollution are moving aft within the channels in the channel portion 16 between the friction elements 3, 3′ and the side walls 11, 11′. In a trial with the collecting device 1, in which the distance between the inlet portion 15 and the end wall 12 was 10.5 m, the velocity of the water was measured at 25 cm depth within one channel at different measuring points. In this trial, the friction elements 3 projected down from the top portion 13. At the inlet portion, the velocity was 0.75 m/s (1.46 knots). After 2 m in the channel portion 16, the velocity was 0.63 m/s; after 5 m in the channel portion 16, the velocity was 0.40 m/s and after 7.5 m in the channel portion 16, the velocity was 0.10 m/s. After 10 m, which was a measuring point in the collecting portion 17, the velocity was 0.01 m/s. According to this trial, an oil film on the water surface 9 will move into the inlet portion 15 at the same velocity as the water. The relative velocity between oil and water in the shear layer is then 0 m/s. After 2 m, the uppermost 25 cm of the water column has been slowed down. The oil film will substantially be at the top of the water column so that the relative velocity between oil and water will still be 0 m/s. Further down the water column, there will be a relative difference in velocity between the slowed-down water and water which is being forced downwards and out of the collecting device 1 at the underside of the end wall 12. By a constant cross section, the relative difference in velocity will be 0.75 m/s−0.63 m/s=0.12 m/s. Because of the tapering cross section of the collecting device 1 from the inlet portion 15 towards the collecting portion 17 as shown in the figures, the relative difference in velocity will be somewhat larger. Still, the relative difference in velocity is smaller than the critical limit of 0.41 m/s leading to a ‘first loss’. The same condition applies after 5 m in the channel portion 16, where the difference in velocity is 0.35 m/s between the measured water velocity and the inlet velocity of the water. After 7.5 m in the channel portion 16, the difference in velocity exceeds the critical limit of 0.41 m/s. However, the water velocity increases gradually with the depth in the water column, so that the relative difference in velocity of the water at 25 cm depth and the water at 30 cm depth after 7.5 m in the channel portion 16, is less than 0.41 m/s and no ‘first loss’ will occur. In this way, a thick oil layer may build up in the collecting portion 17 without the collecting device 1 belching. The thick layer of pollution in the collecting portion 17 may be pumped out.

Without being bound by theory, the achieved slowing-down effect on the water/pollution in the channel portion 16 and the collecting portion 17 is explained by adhesion and/or friction between the side walls 11, 11′ and the water/pollution and adhesion and/or friction between the friction elements 3 and the water/pollution. If the pollution has high viscosity, the collecting device 1 may be without friction elements 3, 3′, so that the channel portion 16 is formed only by the side walls 11, 11′. In a further alternative embodiment, the channel portion 16 of the collecting device 1 may be made narrower than that shown in the figures and may include only one channel formed by the side walls 11, 11′.

Since the collecting device 1 is provided with an open bottom or a bottom capable of through-put in the form of a shape-stabilizing element 6, accumulation and turbulence in front of the inlet portion 15 will be substantially reduced in relation to that of other known solutions. This has the advantage of pollution flowing more easily into the collecting device 1. The collecting device 1 together with the boom may be towed faster along the water surface 9 than other known collecting devices, resulting in larger areas being swept in the same time.

While the invention has been described with a certain degree of particularity, it is manifest that many changes may be made in the details of construction and the arrangement of components without departing from the spirit and scope of this disclosure. It is understood that the invention is not limited to the embodiments set forth herein for purposes of exemplification, but is limited only by the scope of the attached claims, including the full range of equivalency to which each element thereof is entitled. 

1. A collecting device (1) for pollution on a water surface (9), the collecting device (1) comprising: tight side walls (11, 11′); a tight end wall (12); a top portion (13); floating means (2); an inlet portion (15) and an aft collecting portion (17); and a channel portion (16) between the inlet portion (15) and the collecting portion (17) and in the channel portion (16) and the collecting portion (17), a bottom portion of the collecting device (1) has through-put capabilities.
 2. The collecting device (1) in accordance with claim 1, wherein, extending from the inlet portion (15) through the channel portion (16), is at least one friction element (3, 3′).
 3. The collecting device (1) in accordance with claim 2, wherein the at least one friction element (3, 3′) extends to the tight end wall (12).
 4. The collecting device (1) in accordance with claim 2, wherein the at least one friction element (3, 3′) is constituted by a material selected from a group consisting of: a tight material in cloth form; a net; a netting; a perforated material in cloth form.
 5. The collecting device (1) in accordance with claim 2, wherein the at least one friction element (3) is attached at an upper edge portion (31) of the at least one friction element (3) to the top portion (13).
 6. The collecting device (1) in accordance with claim 5, wherein the at least one friction element (3) is releasably attached at an upper edge portion (31) of said friction element (3) to the top portion (13).
 7. The collecting device (1) in accordance with claim 5, wherein the at least one friction element (3) projects freely down into the water at a lower edge portion (33) of said friction element.
 8. The collecting device (1) in accordance with claim 5, wherein, at a lower edge portion of the at least one friction element, the friction element (3) is attached, in a portion, to a shape-stabilizing element (6) capable of through-put.
 9. The collecting device (1) in accordance with claim 1, wherein, in the inlet portion (15), the collecting device (1) is provided with a frame (4) set substantially vertically in position of application.
 10. The collecting device (1) in accordance with claim 9, wherein the at least one friction element (3) is attached at a forward, lower edge portion (33) of said friction element to a lower portion (43) of the frame.
 11. The collecting device (1) in accordance with claim 2, wherein the at least one friction element (3′) is attached at side portions (31′, 33′) to the tight side walls (11, 11′) of the channel portion (16).
 12. The collecting device (1) in accordance with claim 11, wherein the at least one friction element (3′) is releasably attached at side portions (31′, 33′) to the tight side walls (11, 11′) of the channel portion (16).
 13. The collecting device (1) in accordance with claim 1, wherein the top portion (13) is constituted by a tight material in cloth form.
 14. A boom arranged to concentrate pollution on a water surface (9), the boom being provided with an opening in a collecting portion, the boom having in the opening a collecting device (1) in accordance with claim
 1. 